Design a compressed air energy storage for a PV plant

[Ameen1985]

Summary:: Design compressed air energy storage for PV plant

[Mentor Note -- Thread moved from a technical forum, so no Homework Template is shown]

Hi All
For a PV project of 5 kW, we will use a CAES.
The preliminary design will consist of a compressor - 2 heat exchanger - Air receiver - air motor - generator - 2 water tanks as a thermal storage units to have an adiabatic systems.
For a 5 kW PV plant, an energy of 20 to 26 kWh is expected.
At this stage I don't have enough information about the components size and I want to start with the air tank size.
I want to study different sizes and different tank pressures which will accommodate a certain amount of energy.
Any help please?

 

[berkeman]

Welcome to PF.

Is this for schoolwork?

 

[Chestermiller]

Summary:: Design compressed air energy storage for PV plant

Hi All
For a PV project of 5 kW, we will use a CAES.
The preliminary design will consist of a compressor - 2 heat exchanger - Air receiver - air motor - generator - 2 water tanks as a thermal storage units to have an adiabatic systems.
For a 5 kW PV plant, an energy of 20 to 26 kWh is expected.
At this stage I don't have enough information about the components size and I want to start with the air tank size.
I want to study different sizes and different tank pressures which will accommodate a certain amount of energy.
Any help please?

Please show a diagram of your proposed CAES system layout.

 

[Ameen1985]

Welcome to PF.

Is this for schoolwork?

Many thanks for your reply.
It’s for a Uni project

 

[Chestermiller]

Many thanks for your reply.
It’s for a Uni project

Let’s see your flow diagram.

 

[Ameen1985]

Please show a diagram of your proposed CAES system layout.

Many thanks for your reply. It will be something like this

 

[bigfooted]

And what are the design requirements and constraints vor the CAES?

 

[russ_watters]

...specifically, how many kWh do you want to store and/or output? (I assume the generated number was per day).

 

[Ameen1985]

...specifically, how many kWh do you want to store and/or output? (I assume the generated number was per day).

I thought for a preliminary design, I may should think of having an air bottle sufficient for the maximum PV output which is about 26 kWh per day. However, by taking into consideration the required load, about 14 kWh will be stored per day.

 

[Baluncore]

Is this really the size of the problem ?

   1 W·hr = 3600 joule. 
   25 kW·hr = 25000 * 3600 = 90 megajoule
   Cubic metre * pascal = joule

   m3        MPa         Bar          psi
   10        9.000       90.000       1305.
   15        6.000       60.000        870.
   20        4.500       45.000        653.
   25        3.600       36.000        522.
   30        3.000       30.000        435.
   35        2.571       25.714        373.
   40        2.250       22.500        326.
   45        2.000       20.000        290.
   50        1.800       18.000        261.

 

[Ameen1985]

And what are the design requirements and constraints vor the CAES?

I am in the preliminary design stage, so I want to study different options of size vs pressure vs cost. Thermodynamic modelling and charts of different options will be enough now.

 

[Ameen1985]

Is this really the size of the problem ?

   1 W·hr = 3600 joule.
   25 kW·hr = 25000 * 3600 = 90 megajoule
   Cubic metre * pascal = joule

   m3        MPa         Bar          psi
   10        9.000       90.000       1305.
   15        6.000       60.000        870.
   20        4.500       45.000        653.
   25        3.600       36.000        522.
   30        3.000       30.000        435.
   35        2.571       25.714        373.
   40        2.250       22.500        326.
   45        2.000       20.000        290.
   50        1.800       18.000        261.

Many thanks for your reply but I wish it is that simple.
I think for an adiabatic CAES, the pressure outside and inside the vessel, the temperature, a polytropic exponent, and I am not sure is there anything else should be taken into consideration.

 

[russ_watters]

I thought for a preliminary design, I may should think of having an air bottle sufficient for the maximum PV output which is about 26 kWh per day. However, by taking into consideration the required load, about 14 kWh will be stored per day.
...
I am in the preliminary design stage, so I want to study different options of size vs pressure vs cost.

Ok, so this is an optimization problem. You should put together a table listing the possible values. Note; the larger you make your air storage, the smaller your total generation gets.

You should research the requirements to run air motors; how much pressure and flow they need to operate. Then you can match that to a compressor and tank.